During use, heat exchangers used to recover heat from flue gases (called economizers) typically collect soot on the heat exchange tubes that must be periodically removed to maintain the efficiency of the heat exchanger. This has led to the use of soot blowers to direct jets of a pressurized gas such as steam or air over the heat exchanger coils to blow the soot off the heat exchanger tubes.
In economizers where the heat exchanger tubes in the flue gas passage are oriented so that they are normal to the flue gas flow, the soot blower element can be located so that its opposite ends project out of the economizer housing for monitoring. This has permitted a rotary mounting to be used so that the soot blower element can be rotated to achieve a more thorough cleaning of the heat exchange tubes.
In economizers where the heat exchange tubes are formed in a helical coil, however, the soot blower element must be located co-axially with the flue gas flow so that its opposite ends and mountings are exposed to the flue gases. As a result, prior art soot blowers for this type of economizer have been stationarily mounted such as that shown in U.S. Pat. No. 1,954,803 (4/34). The use of a stationary soot blower does not provide the cleaning coverage required in many installations as is possible with the rotary mounting used in the straight tube economizer.
Attempts have been made in the past to provide a rotary mounted soot blower for helical coil economizers. These attempts have not been successful because the rotary mounting failed after a short period of operation.